It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Friday, March 26, 2021
Gene required for jumping identified in rabbits
Experiments with a rare type of rabbit that can't jump pinpointed the necessary gene
VIDEO: PATTERNS OF LOCOMOTION IN SAUTEUR RABBITS. FROM SAMUEL BOUCHER. view more
CREDIT: CARNEIRO M ET AL., 2021, PLOS GENETICS
Rabbits and other hopping animals require a functional RORB gene to move around by jumping, according to a new study by Miguel Carneiro of the Universidade do Porto and Leif Andersson of Uppsala University published March 25th in PLOS Genetics.
Rabbits, hares, kangaroos and some rodent species all travel by jumping, but this type of movement is not well understood on a molecular and genetic level. In the new paper, researchers investigated jumping-related genes using an unusual breed of domesticated rabbit called the sauteur d'Alfort. Instead of hopping, it has a strange gait where it lifts its back legs and walks on its front paws. By breeding sauteur d'Alfort rabbits with another breed and comparing the offspring's genomes and jumping abilities, the researchers identified the cause of this developmental defect. They identified a specific mutation in the RAR related orphan receptor B (RORB) gene. Typically, the RORB protein is found in many regions of the rabbit nervous system, but the mutation leads to a sharp decrease in the number of neurons in the spinal cord that produce RORB. This change is responsible for the sauteur d'Alfort's weird walk.
The new study demonstrates that a functional RORB gene is necessary for rabbits and likely other hopping animals to perform their characteristic jumping gait. The findings build on previous studies in mice, showing that animals that lack the RORB gene had a duck-like walk. Additionally, this work advances our understanding of the different ways that animals with backbones move.
"This study provides a rare example of an abnormal gait behavior mapped to a single base change and the first description of a gene required for saltatorial locomotion," the authors conclude. "It further demonstrates the importance of the RORB protein for the normal wiring of the spinal cord, consistent with previous studies in mouse."
CAPTION
The sauteur d'alfort strain and associated phenotypes. (A) Typical posture of a sauteur rabbit (sam/sam) adopted when jumping (i.e., moving faster or across longer distances). Hindlegs are lifted from the ground, the body is held vertically, and locomotion is achieved through the alternate use of the forelegs. (B) Ocular malformations observed both in sam/sam and +/sam individuals include bilateral papillary colobomas, reduction in pupillary reflexes, bilateral cataracts with lesions in various components of the eye, glaucoma, and/or entropion and ectropion. Taken by (A) R. Cavignaux; (B) S. Boucher.
CREDIT
Carneiro M et al., 2021, PLOS Genetics
Research Article; Peer-reviewed; Experimental study; Animals
Citation: Carneiro M, Vieillard J, Andrade P, Boucher S, Afonso S, Blanco-Aguiar JA, et al. (2021) A loss-of-function mutation in RORB disrupts saltatorial locomotion in rabbits. PLoS Genet 17(3): e1009429. https://doi.org/10.1371/journal.pgen.1009429
Funding: This work was supported by the Fundação para a Ciência e Tecnologia (FCT, https://www.fct.pt/) through POPH-QREN funds from the European Social Fund and Portuguese MCTES (CEECINST/00014/2018/CP1512/CT0002 and IF/00283/2014/CP1256/CT0012); by FEDER funds through the COMPETE program and Portuguese national funds through FCT (projects PTDC/CVT/122943/2010 and PTDC/BIA-EVL/30628/2017); by the project NORTE-01-0145-FEDER-AGRIGEN, supported by the Norte Portugal Regional Operational Programme (NORTE2020) under the PORTUGAL 2020 Partnership Agreement and through the European Regional Development Fund (ERDF); by grants from the Swedish Research Council (KK, LA), the Knut and Alice Wallenberg Foundation (LA), the Swedish Brain Foundation (KK) and the Swedish Foundation for Cooperation in Research and Higher Education (KK); and by travel grants to M.C. (COST Action TD1101). J.V. was supported by a postdoctoral contract from Stiftelsen Promobilia. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.
CTHULHU STUDIES Octopuses sleep study finds they definitely change colors, maybe dream By Katie Hunt, CNN 3/25/2021 With its eight legs wrapped around itself as if in a hug and its eye pupils narrowed to a slit, the octopus breathes evenly, its body a uniform whitish gray.
Moments later it begins to change color -- a mesmerizing shift between burnt orange and rust red. Its eyes, muscles and sucker pads twitching as if it may be experiencing a particularly vivid dream. Brazilian scientists say the shifts in color, behavior and movement are evidence of a sleep cycle -- with the octopus switching between active and quiet sleep just as humans switch between deep sleep and REM sleep -- named for the rapid eye movements we experience in this state. Advertisement
The findings, published Thursday in the journal iScience, show how sleep may have evolved in a similar way in very different creatures and suggests that octopuses may experience something akin to a dream.
"It is not possible to affirm that octopuses dream because they cannot tell us that, but our results suggest that during 'Active sleep' the octopus experiences a state analogous to REM sleep, which is the state during which humans dream the most," said the study authors Sidarta Ribeiro and Sylvia Medeiros in an email.
Ribeiro is a professor of neuroscience at the Brain Institute of the Federal University of Rio Grande do Norte, and Medeiros is a doctoral student at the same university.
Scientists used to think that only mammals and birds experienced different sleep states -- think of a sleeping cat twitching as though it were chasing a bird in the backyard. More recent research, however, has revealed some reptiles and cuttlefish -- another cephalopod and relative of the octopus -- show non-REM and REM-like sleep.
Octopuses have a very different brain structure to humans, but they share some of the same functions as mammal brains. The creatures have special learning abilities -- including being able to solve problems and other sophisticated cognitive abilities, the authors said.
They said investigating octopus sleep was a "vantage point" for comparing them neurobiologically and psychologically with mammals -- with the sleep similarities likely a consequence of "the very taxing mental loads experienced by these separate groups of animals." The octopus has long been a source of human fascination. Video footage from 2019 of an octopus called Heidi changing color as she slept in a tank had scientists wondering if the creatures could really dream. The Netflix documentary "My Octopus Teacher" has also showcased the creatures' unique abilities. Dreaming in GIFs not movies
How were the researchers sure the octopuses they studied were asleep and not just resting? The researchers videoed four members of the Octopus insularis species in their lab and studied the animals' behavior over a period of more than 50 days. The octopuses were very sensitive to very weak stimuli when they were alert, but in both sleep states they needed a strong visual or tactile stimulus to evoke a behavioral response, the scientists said.
Octopuses usually change their skin color for camouflage or for communication but during sleep, environmental factors no longer trigger these patterns. The researchers inferred that the color changes during sleep results from independent brain activity.
The study found that the octopus experiences active sleep after a long episode of quiet sleep. In the case of an octopus, the long period is usually more than six minutes.
"If octopuses indeed dream, it is unlikely that they experience complex symbolic plots like we do. 'Active sleep' in the octopus has a very short duration (typically from a few seconds to one minute)," the authors said via email. "If during this state there is any dreaming going on, it should be more like small videoclips, or even gifs."
Octopuses are known to sleep and to change color while they do it. Now, a study publishing March 25 in the journal iScience finds that these color changes are characteristic of two major alternating sleep states: an "active sleep" stage and a "quiet sleep" stage. The researchers say that the findings have implications for the evolution of sleep and might indicate that it's possible for octopuses to experience something akin to dreams.
Scientists used to think that only mammals and birds had two sleep states. More recently, it was shown that some reptiles also show non-REM and REM sleep. A REM-like sleep state was reported also in cuttlefish, a cephalopod relative of the octopus.
"That led us to wonder whether we might see evidence of two sleep states in octopuses, too," says senior author Sidarta Ribeiro of the Brain Institute of the Federal University of Rio Grande do Norte, Brazil. "Octopuses have the most centralized nervous system of any invertebrate and are known to have a high learning capacity."
To find out, the researchers captured video recordings of octopuses in the lab. They found that during 'quiet sleep' the animals were still and quiet, with pale skin and eye pupils contracted to a slit. During 'active sleep,' it was a different story. The animals dynamically changed their skin color and texture. They also moved their eyes while contracting their suckers and body with muscular twitches.
"What makes it more interesting is that this 'active sleep' mostly occurs after a long 'quiet sleep'--generally longer than 6 minutes--and that it has a characteristic periodicity," Ribeiro says.
The cycle would repeat at about 30- to 40-minute intervals. To establish that these states indeed represented sleep, the researchers measured the octopuses' arousal threshold using visual and tactile stimulation tests. The results of those tests showed that in both 'active' and 'quiet sleep' states, the octopuses needed a strong stimulus to evoke a behavioral response in comparison with the alert state. In other words, they were sleeping.
The findings have interesting implications for octopuses and for the evolution of sleep. They also raise intriguing new questions.
"The alternation of sleep states observed in the Octopus insularis seems quite similar to ours, despite the enormous evolutionary distance between cephalopods and vertebrates, with an early divergence of lineages around 500 million years ago," says first author and graduate student Sylvia Medeiros of the Brain Institute of the Federal University of Rio Grande do Norte, Brazil.
"If in fact two different sleep states evolved twice independently in vertebrates and invertebrates, what are the essential evolutionary pressures shaping this physiological process?" she asks. "The independent evolution in cephalopods of an 'active sleep' analogous to vertebrate REM sleep may reflect an emerging property common to centralized nervous systems that reach a certain complexity."
Medeiros also says that the findings raise the possibility that octopuses experience something similar to dreaming. "It is not possible to affirm that they are dreaming because they cannot tell us that, but our results suggest that during 'active sleep' the octopus might experience a state analogous to REM sleep, which is the state during which humans dream the most," she says. "If octopuses indeed dream, it is unlikely that they experience complex symbolic plots like we do. 'Active sleep' in the octopus has a very short duration--typically from a few seconds to one minute. If during this state there is any dreaming going on, it should be more like small videoclips, or even gifs."
In future studies, the researchers would like to record neural data from cephalopods to better understand what happens when they sleep. They're also curious about the role of sleep in the animals' metabolisms, thinking, and learning.
"It is tempting to speculate that, just like in humans, dreaming in the octopus may help to adapt to environmental challenges and promote learning," Ribeiro says. "Do octopuses have nightmares? Could octopuses' dreams be inscribed on their dynamic skin patterns? Could we learn to read their dreams by quantifying these changes?"
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This work was supported by the State University of Rio Grande do Norte (UERN), the Coordenação de Aperfeicoamento de Pessoal de Nível Superior (CAPES), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), and from the São Paulo Research Foundation (FAPESP) Center for Neuromathematics.
iScience (@iScience_CP) is an open access journal from Cell Press that provides a platform for original research and interdisciplinary thinking in the life, physical, and earth sciences. The primary criterion for publication in iScience is a significant contribution to a relevant field combined with robust results and underlying methodology. Visit http://www.cell.com/iscience. To receive Cell Press media alerts, contact press@cell.com.
IMAGE: HUMPBACK WHALE AND RESEARCHERS PICTURED FROM A DRONE. view more
CREDIT: DUKE MARINE ROBOTICS AND REMOTE SENSING LAB
The ocean's mammals are at a crucial crossroads - with some at risk of extinction and others showing signs of recovery, researchers say.
In a detailed review of the status of the world's 126 marine mammal species - which include whales, dolphins, seals, sea lions, manatees, dugongs, sea otters and polar bears - scientists found that accidental capture by fisheries (bycatch), climate change and pollution are among the key drivers of decline.
A quarter of these species are now classified as being at risk of extinction (vulnerable, endangered or critically endangered on the IUCN Red List), with the near-extinct vaquita porpoise and the critically endangered North Atlantic right whale among those in greatest danger.
Conservation efforts have enabled recoveries among other species, including the northern elephant seal, humpback whale and Guadalupe fur seal.
The international research team - led by the University of Exeter and including scientists from more than 30 institutions in 13 countries - highlight conservation measures and research techniques that could protect marine mammals into the future.
"We have reached a critical point in terms of marine mammal conservation," said lead author Dr Sarah Nelms, of the Centre for Ecology and Conservation on Exeter's Penryn Campus in Cornwall.
"Very few marine mammal species have been driven to extinction in modern times, but human activities are putting many of them under increasing pressure.
"Our paper examines a range of conservation measures - including Marine Protected Areas (MPAs), bycatch reduction methods and community engagement - as well as highlighting some of the species that are in urgent need of focus."
The researchers say 21% of marine mammal species are listed as "data deficient" in the IUCN Red List - meaning not enough is known to assess their conservation status.
This lack of knowledge makes it difficult to identify which species are in need of protection and what actions should be taken to save them.
Professor Brendan Godley, who leads the Exeter Marine research group, said: "To continue conservation successes and reverse the downward trend in at-risk species, we need to understand the threats they face and the conservation measures that could help.
"Technology such as drone and satellite imaging, electronic tags and molecular techniques are among the tools that will help us do this.
"Additionally, sharing best practice will empower us - and this is why we are so proud to be part of such a large and international group for this project."
The paper, published in the journal Endangered Species Research, is entitled: "Marine mammal conservation: Over the horizon."
CAPTION
Hawaiian spinner dolphins.
CREDIT
Rob Harcourt
CAPTION
Weddell seal.
CREDIT
Rob Harcourt
Two new species of already-endangered screech owls discovered in Amazon rainforest
Recordings of owls' screeches used to help tell species apart
IMAGE: ONE OF THE NEWLY DESCRIBED SPECIES, THE XINGU SCREECH OWL. view more
CREDIT: KLEITON SILVA
The Amazon rainforest is teeming with creatures unknown to science--and that's just in broad daylight. After dark, the forest is a whole new place, alive with nocturnal animals that have remained even more elusive to scientists than their day-shift counterparts. In a new paper in Zootaxa, researchers described two new species of screech owls that live in the Amazon and Atlantic forests, both of which are already critically endangered.
"Screech owls are considered a well-understood group compared to some other types of organisms in these areas," says John Bates, curator of birds at the Field Museum in Chicago and one of the study's authors. "But when you start listening to them and comparing them across geography, it turns out that there are things that people hadn't appreciated. That's why these new species are being described."
"Not even professional ornithologists who have worked on owls for their entire lives would agree about the actual number of species found in this group, so a study like ours has been awaited for a really long time," says Alex Aleixo, head of the research team responsible for the study, and currently curator of birds at the Finnish Museum of Natural History in the University of Helsinki, Finland.
The newly-discovered screech owls are cousins of the Eastern Screech Owls that are common in the United States. "They're cute little owls, probably five or six inches long, with tufts of feathers on their heads," says Bates. "Some are brown, some are gray, and some are in between." Until this study, the new species were lumped together with the Tawny-bellied Screech Owl and the Black-capped Screech Owl, which are found throughout South America.
Teasing out the differences between the species started with years of fieldwork in the Amazon rainforest as well as the Atlantic forest running along the eastern part of Brazil and surrounding countries. Bates, who usually conducts fieldwork during the day, says that doing fieldwork in the rainforest at night comes with new challenges. "For me it's more a feeling of fascination than being scared, but at the same time, you're running into spider webs. If you're wearing a headlight you see the eyeshine of the nocturnal animals. One time I was stepping over a log and I looked down and there was a tarantula the size of my hand just sitting there," says Bates. "If I had been a kid I would have been scared to death."
The owls that the researchers were looking for live in the trees, often a hundred feet above the forest floor. That makes studying them difficult. But the researchers had a secret weapon: the screech owls' namesake screech.
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One of the newly described species, the Alagoas Screech Owl.
CREDIT
Gustavo Malacco.
"To draw the birds out, we used tape recordings," explains Bates. "We'd record their calls and then play them back. The owls are territorial, and when they heard the recordings, they came out to defend their territory."
The scientists compared the birds' calls and found that there were variations in the sounds they made, indicative of different species. They also examined the birds' physical appearances and took tissue samples so they could study the owls' DNA at the Field Museum's Pritzker DNA Lab.
Altogether, 252 specimens, 83 tape-recordings, and 49 genetic samples from across the range of the Tawny-bellied Screech Owl complex in South America were analyzed. A significant number of specimens were collected by the research team itself, especially the study's lead author Sidnei Dantas, who spent a good share of his time in graduate school searching for and tape-recording screech owls in South American rainforests. In addition, natural history collections and their materials collected over the centuries were essential to complete the study´s unprecedented sampling.
"The study would not have been possible if it were not for the great biological collections in Brazil and USA which I visited during my work, and that sent us essential material, either genetic and morphological. This highlights the importance of such research institutions for the progress of science and hence of the countries they represent," says Dantas, who conducted the study as part of his PhD dissertation at the Goeldi Museum in Belém and is currently working as a nature guide in Brazilian Amazonia.
The combination of genetic variation, physical differences, and unique vocalizations led the team to describe two new species in addition to the previously known Tawny-bellied Screech Owl: the Xingu Screech Owl and the Alagoas Screech Owl. The Xingu owl's scientific name is in honor of Sister Dorothy May Stang, an activist who worked with Brazilian farmers to develop sustainable practices and fight for their land rights; its common name is for the area where the owl is found near the Xingu River. The Alagoas owl's name is a reference to the northeastern Brazilian state of Alagoas where the owl is primarily found.
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Lead author Sidnei Dantas working with owl specimens at the Field Museum.
CREDIT
John Bates, Field Museum
While the owls are new to science, they're already in danger of disappearing forever. "Both new species are threatened by deforestation," says Jason Weckstein, associate curator of Ornithology in the Academy of Natural Sciences of Drexel University and associate professor in the university's Department of Biodiversity, Earth, and Environmental Science. "The Xingu Screech Owl is endemic to the most severely burned area of the Amazon by the unprecedented 2019 fires, and the Alagoas Screech Owl should be regarded as critically endangered given the extensive forest fragmentation in the very small area where it occurs," says Weckstein, who is a co-author and began work on this project as a postdoctoral researcher at the Field Museum.
Bates says he hopes that the study will shed light on how varied the Amazon and Atlantic forests are and how simply protecting certain areas isn't enough to preserve the forests' biodiversity. "If you just say, 'Well, you know Amazonia is Amazonia, and it's big,' you don't end up prioritizing efforts to keep forests from being cut in these different parts of Amazonia. That could mean losing entire faunas in this region," says Bates.
In addition to the study's conservation implications, the authors highlight the international collaboration that made the work possible. "This study shows how important it is to train the next generation of scientists at a global level," says Bates. "That means to having students like Sidnei come from Brazil and work in the Field's Pritzker Lab and measure specimens in our collection for their research. It's a great thing to build those connections."
IMAGE: BACTERIAL COLONIES OF THE CYANOBACTERIUM A. HYDRILLICOLA GROWING ON A LEAF OF THE INVASIVE AQUATIC PLANT H. VERTICILLATA. view more
CREDIT: SUSAN WILDE
Bald eagles, as well as other wildlife, have been succumbing to a mysterious neurodegenerative disease in the southern United States since the 1990s. New research by the Martin Luther University Halle-Wittenberg (MLU) in Germany and the University of Georgia, USA, identifies the cause of these deaths: a toxin produced by cyanobacteria that grow on invasive aquatic plants. The problem is potentially exacerbated by herbicides used to control those plants. The results were published in Science.
In 1994, bald eagles were dying on a mass scale in the U.S. state of Arkansas. The animals were losing control over their bodies, and holes were developing in their brains. A previously unknown neurodegenerative disease, termed vacuolar myelinopathy (VM), was identified. "The origin of the disease was a complete mystery," says Professor Timo Niedermeyer from the Institute of Pharmacy at MLU.
Later on, American researchers found that not only eagles were affected, but also their herbivorous prey. The scientists discovered a connection to an invasive aquatic plant (Hydrilla verticillata) that grows in freshwater lakes in the affected regions. However, there were still some lakes with the aquatic plant where the disease was not manifesting. In 2005 Susan B. Wilde, a professor at the Warnell School of Forestry and Natural Resources at the University of Georgia, identified a previously unknown cyanobacterium on the leaves of Hydrilla verticillata, which appeared to be the cause of the disease. It turned out that vacuolar myelinopathy only occurs in places where the cyanobacterium colonizes the invasive plant. She called the bacterium "eagle killer that grows on Hydrilla": Aetokthonos hydrillicola.
"I stumbled across a press release issued by the university in Georgia and was fascinated by these findings, because I've worked with cyanobacteria for years," says Niedermeyer. He had samples sent to him, cultivated the bacteria in the laboratory and sent them back to the U.S. for further testing. But the tests came back negative: The bacteria from the lab did not induce the disease. "It's not just the birds that were going crazy, we were too. We wanted to figure this out," says Niedermeyer. Once again, he had colonized leaves sent to him. Steffen Breinlinger, a doctoral student in his research group, then used a new imaging mass spectrometer to investigate the composition on the surface of the plant's leaf, molecule by molecule. He discovered a new substance that only occurs on the leaves where the cyanobacteria grow, but is not produced in the cultivated bacteria.
His investigations into the chemical structure of the isolated molecule showed that it contains five bromine atoms. "The structure is really spectacular," says Breinlinger. The properties are unusual for a molecule formed by bacteria. And they provide an explanation for why the toxin did not form under laboratory conditions. Standard culture media in which cyanobacteria grow do not contain bromide. "We then added bromide to our lab cultures, and - the bacteria started producing the toxin," says Breinlinger. Wilde and her colleagues tested the isolated molecule in birds, and finally, after almost a decade of research in the Wilde and Niedermeyer labs, they had the proof: the molecule does trigger VM. According to the name of the bacterium, the researchers call their discovery aetokthonotoxin, "poison that kills the eagle". "Finally, we did not only catch the murderer, but we also identified the weapon the bacteria use to kill those eagles," says Wilde.
A research group participating in the study from the Czech Academy of Sciences also found sections of DNA containing genetic information for the synthesis of the new molecule. Why the cyanobacteria form the toxin on the aquatic plants in the first place, however, has yet to be studied. One of the herbicides used to combat the invasive aquatic plant might play a crucial part in VM occurrence: It contains bromide and thus might stimulate toxin production.
The neurological disease has not yet occurred in Europe, and no instance of the toxin-forming cyanobacterium has been reported.
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The research has been supported by the Deutsche Forschungsgemeinschaft (German Research Foundation, DFG), the Czech Science Foundation GA?R, the US Department of Interior, US Fish and Wildlife Service, the Florida Fish & Wildlife Conservation Commission, the Gulf States Marine Fisheries Commission, the National Institute of Food and Agriculture McIntire-Stennis Capacity Grant and the American Eagle Foundation.
IMAGE: XYLEM TISSUE IN GYMNOSPERM SAPWOOD CAN BE USED?FOR?WATER FILTRATION (AS SEEN ON TOP). XYLEM IS COMPRISED OF CONDUITS THAT ARE INTERCONNECTED?BY MEMBRANES THAT? FILTER OUT?CONTAMINANTS PRESENT IN WATER (BOTTOM).... view more
CREDIT: COURTESY: N.R. FULLER, SAYO STUDIO
The interiors of nonflowering trees such as pine and ginkgo contain sapwood lined with straw-like conduits known as xylem, which draw water up through a tree's trunk and branches. Xylem conduits are interconnected via thin membranes that act as natural sieves, filtering out bubbles from water and sap.
MIT engineers have been investigating sapwood's natural filtering ability, and have previously fabricated simple filters from peeled cross-sections of sapwood branches, demonstrating that the low-tech design effectively filters bacteria.
Now, the same team has advanced the technology and shown that it works in real-world situations. They have fabricated new xylem filters that can filter out pathogens such as E. coli and rotavirus in lab tests, and have shown that the filter can remove bacteria from contaminated spring, tap, and groundwater. They also developed simple techniques to extend the filters' shelf-life, enabling the woody disks to purify water after being stored in a dry form for at least two years.
The researchers took their techniques to India, where they made xylem filters from native trees and tested the filters with local users. Based on their feedback, the team developed a prototype of a simple filtration system, fitted with replaceable xylem filters that purified water at a rate of one liter per hour.
Their results, published today in Nature Communications, show that xylem filters have potential for use in community settings to remove bacteria and viruses from contaminated drinking water.
The researchers are exploring options to make xylem filters available at large scale, particularly in areas where contaminated drinking water is a major cause of disease and death. The team has launched an open-source website, with guidelines for designing and fabricating xylem filters from various tree types. The website is intended to support entrepreneurs, organizations, and leaders to introduce the technology to broader communities, and inspire students to perform their own science experiments with xylem filters.
"Because the raw materials are widely available and the fabrication processes are simple, one could imagine involving communities in procuring, fabricating, and distributing xylem filters," says Rohit Karnik, professor of mechanical engineering and associate department head for education at MIT. "For places where the only option has been to drink unfiltered water, we expect xylem filters would improve health, and make water drinkable."
Karnik's study co-authors are lead author Krithika Ramchander and Luda Wang of MIT's Department of Mechanical Engineering, and Megha Hegde, Anish Antony, Kendra Leith, and Amy Smith of MIT D-Lab.
Clearing the way
In their prior studies of xylem, Karnik and his colleagues found that the woody material's natural filtering ability also came with some natural limitations. As the wood dried, the branches' sieve-like membranes began to stick to the walls, reducing the filter's permeance, or ability to allow water to flow through. The filters also appeared to "self-block" over time, building up woody matter that clogged the conduits.
Surprisingly, two simple treatments overcame both limitations. By soaking small cross-sections of sapwood in hot water for an hour, then dipping them in ethanol and letting them dry, Ramchander found that the material retained its permeance, efficiently filtering water without clogging up. Its filtering could also be improved by tailoring a filter's thickness according to its tree type.
The researchers sliced and treated small cross-sections of white pine from branches around the MIT campus and showed that the resulting filters maintained a permeance comparable to commercial filters, even after being stored for up to two years, significantly extending the filters' shelf life.
The researchers also tested the filters' ability to remove contaminants such as E. coli and rotavirus -- the most common cause of diarrheal disease. The treated filters removed more than 99 percent of both contaminants, a water treatment level that meets the "two-star comprehensive protection" category set by the World Health Organization.
"We think these filters can reasonably address bacterial contaminants," Ramchander says. "But there are chemical contaminants like arsenic and fluoride where we don't know the effect yet," she notes.
Groundwork
Encouraged by their results in the lab, the researchers moved to field-test their designs in India, a country that has experienced the highest mortality rate due to water-borne disease in the world, and where safe and reliable drinking water is inaccessible to more than 160 million people.
Over two years, the engineers, including researchers in the MIT D-Lab, worked in mountain and urban regions, facilitated by local NGOs Himmotthan Society, Shramyog, Peoples Science Institute, and Essmart. They fabricated filters from native pine trees and tested them, along with filters made from ginkgo trees in the U.S., with local drinking water sources. These tests confirmed that the filters effectively removed bacteria found in the local water. The researchers also held interviews, focus groups, and design workshops to understand local communities' current water practices, and challenges and preferences for water treatment solutions. They also gathered feedback on the design.
"One of the things that scored very high with people was the fact that this filter is a natural material that everyone recognizes," Hegde says. "We also found that people in low-income households prefer to pay a smaller amount on a daily basis, versus a larger amount less frequently. That was a barrier to using existing filters, because replacement costs were too much."
With information from more than 1,000 potential users across India, they designed a prototype of a simple filtration system, fitted with a receptacle at the top that users can fill with water. The water flows down a 1-meter-long tube, through a xylem filter, and out through a valve-controlled spout. The xylem filter can be swapped out either daily or weekly, depending on a household's needs.
The team is exploring ways to produce xylem filters at larger scales, with locally available resources and in a way that would encourage people to practice water purification as part of their daily lives -- for instance, by providing replacement filters in affordable, pay-as-you-go packets.
"Xylem filters are made from inexpensive and abundantly available materials, which could be made available at local shops, where people can buy what they need, without requiring an upfront investment as is typical for other water filter cartridges," Karnik says. "For now, we've shown that xylem filters provide performance that's realistic."
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This research was supported, in part, by the Abdul Latif Jameel Water and Food Systems Lab (J-WAFS) at MIT and the MIT Tata Center for Technology and Design.
IMAGE: BUNCHES IN AN OIL PALM PLANTATION IN INDONESIA. IT TAKES ABOUT 38 WEEKS FROM INITIATION UNTIL BUNCHES ARE READY FOR HARVEST. view more
CREDIT: HENDRA SUGIANTO/UNIVERSITY OF NEBRASKA-LINCOLN
Lincoln, Neb., March 25, 2021 -- Palm oil, the most important source of vegetable oil in the world, is derived from the fruit of perennial palm trees, which are farmed year-round in mostly tropical areas. The palm fruit is harvested manually every 10 days to two weeks, then transported to a mill for processing, and ultimately exported and made into a dizzying array of products from food to toiletries to biodiesel.
"You probably ate palm oil for breakfast," said Patricio Grassini, an associate professor of agronomy at the University of Nebraska-Lincoln. "There is probably palm oil in your shampoo and for sure palm oil in your makeup."
Dozens of countries produce palm oil, but Indonesia produces approximately two-thirds of the world's supply, and demand for the product is ever-growing.
This is a double-edged sword for Indonesia and other palm-oil producing countries, Grassini said. Palm oil is a major export and contributes to the economic stability of countries that are major producers, as well as to the individual farmers who produce it. But to keep up with demand, rainforests and peatlands - valuable ecosystems that contribute greatly to biodiversity -- are often converted to palm production.
A four-year research project led by Grassini and supported by a $4 million grant from the Norwegian Ministry of Foreign Affairs suggests that keeping up with demand may not necessarily mean converting more valuable, fragile ecosystems into agricultural land.
According to research published March 25 in Nature Sustainability, palm oil yields on existing farms and plantations could be greatly increased with improved management practices. Researchers from the Indonesian Oil Palm Research Institute, the Indonesian Agency for Agriculture Research and Development, and Wageningen University in the Netherlands were also part of this project.
In Indonesia, about 42% of land used for palm oil production is owned by small holder farmers, with the rest managed by large plantations, said Juan Pablo Monzon, a UNL research assistant professor of agronomy and horticulture and first author of the published paper. "There is great potential to increase productivity of current plantations, especially in the case of smallholders' farms, where current yield is only half of what is attainable."
The research shows that palm farmers have significant opportunity to increase their production, said Grassini, one of the developers of the Global Yield Gap Atlas, a collaboration between UNL and Wageningen University in the Netherlands designed to estimate the difference between actual and potential yields for major food crops worldwide including palm oil.
"The potential impact is huge, and if we are able to realize some of that potential, that means a lot in terms of reconciling economic and environmental goals," Grassini said. "If we can produce more, we don't need to expand into new areas. But this would require the effective implementation of current Indonesia government policy and assuring that regulations are enforced so that intensification and productivity gains translate into sparing critical natural ecosystems."
The gap between the current and attainable yields could be bridged by implementing good agronomic practices, Monzon said. As a result, the country could produce 68% more palm oil on existing plantation area located in mineral soils.
Grassini and other researchers identified key management practices that could lead to larger yields. Those practices include improved harvest methods, better weed control, improved pruning and better plant nutrition. Grassini and other researchers now are working with producers, non-government organizations, Indonesian government officials and a host of other partners to put these management techniques into practice. Already they have begun to see improvements in yields.
This is exciting from both environmental and economic standpoints, Grassini said. It also stands to have a great impact on the millions of individual farmers who draw their livelihood from small palm farms often comprised of just a few acres.
"Whatever we do to help the farmers produce more palm oil on the land that they have directly impacts their income and directly impacts their families," Grassini said. "It could be the difference between sending kids to school or not."
The first phase of the research - the research that identified the yield gap - was surprising, Grassini said. Indonesia had already gone through a period of agricultural intensification that had resulted in better yields for rice and corn, and he hadn't anticipated quite so much room for improvement when it came to palm oil.
But it's the second phase of the research that really excites him. So many people from so many different backgrounds are all working together to fine-tune management strategies and put them into practice. After just 15 months, yields on test plots are already up, with potential for more growth in the future. Robust education and extension efforts will be key to fully exploit the potential for growth, Grassini said.
"I don't think you will find too many projects where people are working side-by-side on the production side, science side and environmental side," Grassini said. "All are bringing real solutions to the table and together can have a massive impact."
CAPTION
Young oil palm plantation in Indonesia. Each plantation cycle is about 25 years.
CREDIT
Hendra Sugianto/University of Nebraska-Lincoln
Inhibiting impact of dust aerosols on eastern Pacific tropical cyclones from the perspective of energy transmission
INSTITUTE OF ATMOSPHERIC PHYSICS, CHINESE ACADEMY OF SCIENCES
IMAGE: SCHEMATIC OF THE NEGATIVE EFFECT OF DUST AEROSOLS ON THE ENERGY TRANSMISSION OF TC. view more
CREDIT: ZHENXI ZHANG
The thermodynamic state of the tropical atmosphere plays an important role in the development of tropical cyclone (TC) intensity. A TC imports thermodynamic energy from ocean-air heat and moisture fluxes and exports heat aloft at the much colder upper troposphere, through a radially and vertically directed overturning circulation in a TC. The work done through this cycle drives the TC's winds.
A negative response of cloud water in the lower troposphere to dust aerosol optical depth (AOD) has recently been reported in Atmospheric and Oceanic Science Letters (https://doi.org/10.1016/j.aosl.2020.100028) by Dr. Zhenxi Zhang from the Inner Mongolia University of Technology, Hohhot, China, by analyzing MERRA-2 reanalysis data and GCM simulations from CMIP6.
"The explanation of this response could be that dust aerosols absorb solar radiation, promoting the evaporation of clouds. In principle, this aerosol-driven vaporization modification could affect the enthalpy of the air surrounding a tropical cyclone", explains Dr. Zhang.
According to Zhang's study, a negative association between eastern Pacific TC intensity in offshore regions and dust AOD for the years 1980-2019 was also found. "The changes in TC intensity related to dust AOD conditions should be a consequence of the anomalous enthalpy of the air surrounding a TC caused by the negative effect of dust on cloud water", concludes Zhang.
